403 research outputs found
Fermion spectrum and localization on kinks in a deconstructed dimension
We study the deconstructed scalar theory having nonlinear interactions and
being renormalizable. It is shown that the kink-like configurations exist in
such models. The possible forms of Yukawa coupling are considered. We find the
degeneracy in mass spectrum of fermions coupled to the nontrivial scalar
configuration.Comment: 19pages, 39figures, revised versio
Laplacian spectral characterization of roses
A rose graph is a graph consisting of cycles that all meet in one vertex. We
show that except for two specific examples, these rose graphs are determined by
the Laplacian spectrum, thus proving a conjecture posed by Lui and Huang [F.J.
Liu and Q.X. Huang, Laplacian spectral characterization of 3-rose graphs,
Linear Algebra Appl. 439 (2013), 2914--2920]. We also show that if two rose
graphs have a so-called universal Laplacian matrix with the same spectrum, then
they must be isomorphic. In memory of Horst Sachs (1927-2016), we show the
specific case of the latter result for the adjacency matrix by using Sachs'
theorem and a new result on the number of matchings in the disjoint union of
paths
Effect of preservation method and storage condition on ascorbic acid loss in beverages
Global market is flooded with vitamin-enriched foods, mainly beverages. Major vitamins for enriching beverages are the antioxidant vitamins A, C and E. Ascorbic acid is readily oxidized and lost during storage of the beverages, at rates depending on the conditions of storage. This fact is of great importance for the consumer who must know how to store beverages and when to consume them in order to get the maximum benefit of added vitamin C. The objective of this paper was to determine the amount of ascorbic acid lost in beverages applying different preservation methods and storage condition. Beverage was made in laboratory conditions with synthetic L-ascorbic acid added according to the national legislations. After 30 days of storage at 4-8oC ascorbic acid overall loss was from 81.01% to 90.27% in thermally pasteurized samples and from 97.83 % to almost complete loss in samples preserved with sodium benzoate
Relative-coordinate determination for visual double stars by applying Fourier transforms
We discuss the software developed for the purpose of determining the relative
coordinates (position angle θ and separation ρ) for visual double or
multiple stars. It is based on application of Fourier transforms in treating
CCD frames of these systems. The objective was to determine the relative
coordinates automatically to an extent as large as possible. In this way the
time needed for the reduction of many CCD frames becomes shorter. The
capabilities and limitations of the software are examined. Besides, the
possibility of improving is also considered. The software has been tested
and checked on a sample consisting of CCD frames of 165 double or multiple
stars obtained with the 2m telescope at NAO Rozhen in Bulgaria in October
2011. The results have been compared with the corresponding results obtained
by applying different software and the agreement is found to be very good
Frame Permutation Quantization
Frame permutation quantization (FPQ) is a new vector quantization technique
using finite frames. In FPQ, a vector is encoded using a permutation source
code to quantize its frame expansion. This means that the encoding is a partial
ordering of the frame expansion coefficients. Compared to ordinary permutation
source coding, FPQ produces a greater number of possible quantization rates and
a higher maximum rate. Various representations for the partitions induced by
FPQ are presented, and reconstruction algorithms based on linear programming,
quadratic programming, and recursive orthogonal projection are derived.
Implementations of the linear and quadratic programming algorithms for uniform
and Gaussian sources show performance improvements over entropy-constrained
scalar quantization for certain combinations of vector dimension and coding
rate. Monte Carlo evaluation of the recursive algorithm shows that mean-squared
error (MSE) decays as 1/M^4 for an M-element frame, which is consistent with
previous results on optimal decay of MSE. Reconstruction using the canonical
dual frame is also studied, and several results relate properties of the
analysis frame to whether linear reconstruction techniques provide consistent
reconstructions.Comment: 29 pages, 5 figures; detailed added to proof of Theorem 4.3 and a few
minor correction
Mineral and chemical composition particles in the atmosphere Kolubara basin zone and environmental impact
Čestice iz vazduha su prikupljane u blizini termoelektrane i površinskih kopova
rudnika uglja u Kolubarskom basenu. Izmereni srednji sadržaji koncentracija rastvornih,
nerastvornih i ukupnih taložnih materija na godišnjem nivou prelaze 200 mg/m2dan (K-
1, K-3, K-4, K-5). Distribucija čestica na svim lokacijama klasifikovana je na čestice
veličine veće od 10 μm, zatim na čestice veličine od 10 μm do 2,5 μm i klase čestica
veličine ispod 2,5 μm. Ovakva podela je dala odnos koncentracija inhalatornih i
respiratornih čestica po mernim mestima. Skenirajuća elektronska mikroskopija je
pokazala da prašina iz rudnika uglja i termoelektrane se sastoji u velikoj meri od skupa
mineralnih zrna i čestica uglja. Takođe, SEM-EDX analize su pokazale da je mineralni
sastav aerosedimenata i PM10 čestica heterogen i da se stalno menja. Ovi nalazi su
podržani i analitičkim ispitivanjima rendgenskom difrakcijom praha koja je dala sličan
mineralni sastav (kvarc, feldspati, gline, gips, dolomit, kalcit, liskuni, hlorit i hematit).
Hemijski sastav aerosedimenata i PM10 čestica pokazao je dominantno učešće oksida
SiO2, Al2O3 i Fe2O3 a i obogaćen sadržajima mnogih toksičnih elemenata kao npr. (Pb,
Zn, As, Cd, Co, Hg, Cr). Ovaj rad pokazuje da je koncentracija čestica, mineraloška i
hemijska karakterizacija vazdušnih čestica iz rudnika i termoelektrane presudna za
frakcije koje se udišu, i za identifikaciju potencijalno opasnih (hazardnih) komponenata
u aerosedimentima i suspendovanim česticama (PM10). Koncentracije mikroelemenata u
PM10 česticama su ukazali da As i Co u Lazarevcu i Cd u Velikim Crljenima su iznad
maksimalno dozvoljenih vrednosti. Najveća zabrinutost je za koncentracije As i Cd, dva
jako toksična elementa koja inhalacijom mogu izazvati teške bolesti. Utvrđena je
zastuplenost arsena u aerosedimentima čije su koncentracije preko dnevnog unosa tako
da postoji opravdana bojazan o izazivanju bolestibolesti udisanjem ovog metalau
ispitivanom području...The airborne particles were collected near the power plant and the opencast coal
mine of the Kolubara basin. The measured averages of the concentration soluble,
insoluble and total particulate matter per year exceed 200 mg/m2 per day (K-1, K-3, K-
4, K-5). The particle distribution at all sites was classified in three classes: the particles
larger than 10 μm, the particles from 10 to 2.5 μm and the particles below 2.5 μm. This
division has given the concentration ratio of inhaled and respiratory particles per
measuring points. Scanning electron microscopy showed that the dust from coal mines
and power plants largely consist of a set of mineral grains and coal particles. SEM-EDX
analysis also showed that the mineral composition of aero sediments and PM10 particles
is heterogeneous and constantly changing. These findings were also supported by
analytical studies of X-ray powder diffraction which has made a similar mineral
composition (quartz, feldspar, clay, gypsum, dolomite, calcite, mica, chlorite, and
hematite). Chemical composition of aero sediments and PM10 particles has shown
dominant share of oxides SiO2, Al2O3 and Fe2O3 enriched with the contents of many
toxic elements (such as Pb, Zn, As, Cd, Co, Hg, Cr). This paper shows that the
concentration of particles, mineralogical and chemical characterization of air particles
from coal mine and power plant, is crucial for the inhalation fractions, and for the
identification of potentially dangerous (hazardous) components in air sediments and
particulate matter (PM10). Concentrations of microelements in PM10 particles indicated
that As and Co in Lazarevac and Cd in Veliki Crljeni are above the maximum permitted
level. The biggest concern is for the concentration of As and Cd, two highly toxic
elements that can cause serious illness inhaling. The presence of arsenic in air sediments
whose concentrations exceed the daily intake was determined so that there is a
legitimate fear in the investigated area of causing disease by inhalation of these metals..
Mehaničko ponašanje spregnutih konstrukcija tipa drvo-beton
The subject of the scientific research are composite structures type timber-concrete with the special attention to the mechanical beha-viour, of both, composite system as a whole and all the containing elements: concrete plate, timber beam and adequate connecting sys-tems. The essence of the work is in the comparative analytical-nume-rical-experimental analysis of two series of composite beams of the timber-concrete type by different connecting systems. The conclu-sions have been formed on the base of the experimental testing of beams up to the collapse in the adequate laboratory conditions, nu-merical modelling using the software ABAQUS and analytical nu-merical method according to the postulates of the theory of elasticity, defined in Annex B, Eurocode 5. Besides testing the beams according to static loading bending to the collapse, the work provides the data about the huge correlated research in order to determine mechanical constants of the adequate strength and stiffnesses, as well as the physical characteristics of the used timber and concrete material for making experimental samples. The special attention has been dedica-ted to determining the sliping parameters of connecting systems which were used while making composite beams. All the experiments have been carried out in accordance with the modern procedures contained in the suitable codes
Ocena stopnia zaawansowania miażdżycy u dzieci i młodzieży z cukrzycą typu 1
Introduction: To evaluate the degree of atherosclerosis in children and adolescents with type 1 diabetes and its correlation with risk factors,
traditional and other, such as anti-oxidative capacity of circulating blood and level of lipid peroxidation.
Material and methods: Forty children and adolescents with type 1 diabetes with mean age 13.7 years were compared with 20 age- and
sex-matched healthy control subjects. Association of carotid artery intima-media thickness (cIMT) with different risk factors measured in
children with type 1 diabetes was evaluated.
Results: Mean carotid IMT was higher in subjects with diabetes (p < 0.01) and was strongly associated with total cholesterol with an odds
ratio of 4.08 (p = 0.016), LDL-cholesterol with an odds ratio of 2.78 (p = 0.037), length of disease with an odds ratio of 1.87 (p = 0.007)
and positive family history (first- and second-degree relatives) of diabetes and early CVD (heart attack and/or stroke before the age of 60
years) with an odds ratio of 6.8 (p = 0.007).
Conclusions: We found significantly increased cIMT in the diabetic patients compared to the healthy control subjects. Risk factors for
the development of atherosclerosis included higher total and LDL-cholesterol, higher systolic blood pressure, positive family history of
diabetes and early CVD and longer diabetes duration. In spite of the documented increased oxidative stress, we failed to establish a correlation
between the oxidative stress parameters and cIMT values. (Endokrynol Pol 2012; 63 (6): 414–419)Wstęp: Ocena stopnia zaawansowania miażdżycy u dzieci i młodzieży z cukrzycą typu 1 oraz jego korelacja z czynnikami ryzyka, tradycyjnymi
i innymi, na przykład potencjałem antyoksydacyjnym krwi krążącej i poziomem peroksydacji lipidów.
Materiał i metody: Porównano 40 dzieci i nastolatków z cukrzycą typu 1, średnia wieku 13,7 roku, z 20 zdrowymi osobnikami stanowiącymi
grupę kontrolną odpowiednio dobranymi pod względem wieku i płci. Oceniano związek pomiędzy grubością kompleksu błony
wewnętrznej i środkowej tętnic szyjnych (cIMT) a różnymi czynnikami ryzyka ocenianymi ilościowo u dzieci z cukrzycą typu 1.
Wyniki: Średnia wartość cIMT była większa u pacjentów z cukrzycą (p < 0,01) i wykazywała silny związek ze stężeniem cholesterolu
całkowitego [iloraz szans (OR) 4,08; p = 0,016], cholesterolem frakcji LDL (OR 2,77; p = 0,037), czasem trwania choroby (OR 1,87; p =
0,007) i dodatnim wywiadem rodzinnym (krewni pierwszego i drugiego stopnia) w kierunku cukrzycy i wczesnego występowania chorób
układu krążenia (zawału serca i/lub udaru mózgu przed 60. rokiem życia) (OR 6,8; p = 0,007).
Wnioski: Stwierdzono znamiennie podwyższoną wartość cIMT u pacjentów z cukrzycą w porównaniu ze zdrowymi osobnikami z grupy
kontrolnej. Czynniki ryzyka rozwoju miażdżycy obejmowały podwyższone stężenie cholesterolu całkowitego i cholesterolu frakcji LDL,
podwyższone skurczowe ciśnienie tętnicze, dodatni wywiad rodzinny w kierunku cukrzycy i wczesnego występowania chorób układu
krążenia oraz dłuższy czas trwania cukrzycy. Pomimo udokumentowanego wzmożenia stresu oksydacyjnego nie udało się ustalić korelacji
pomiędzy parametrami stresu oksydacyjnego a wartościami cIMT. (Endokrynol Pol 2012; 63 (6): 414–419
Spectral Measures of Bipartivity in Complex Networks
We introduce a quantitative measure of network bipartivity as a proportion of
even to total number of closed walks in the network. Spectral graph theory is
used to quantify how close to bipartite a network is and the extent to which
individual nodes and edges contribute to the global network bipartivity. It is
shown that the bipartivity characterizes the network structure and can be
related to the efficiency of semantic or communication networks, trophic
interactions in food webs, construction principles in metabolic networks, or
communities in social networks.Comment: 16 pages, 1 figure, 1 tabl
Cracking resistance of AlMg4.5Mn alloy TIG welded joints
In this paper the AlMg4.5Mn TIG welded joints have been tested in order to investigate their cracking resistance. Testing plates, size of 500×250×12 mm, are welded by TIG procedure in a horizontal-vertical position. Various mixtures of inert gases are prepared and supplied by MESSER TEHNOGAS AD, Smederevo (Serbia), including Ar, Ar + 0.015% N 2 , Ar + 15% He + 0.015% N 2 , Ar + 30% He + 0.015% N 2 , Ar + 50% He + 0.015% N 2 . Nondestructive testing is used to check joint defects, primarily porosity, as typical for this type of alloys. The Charpy specimens, with the notch positioned in different regions of the welded joint, are tested using instrumented pendulum to separate crack initiation and growth energy. Crack resistance is evaluated by using static (KIc) and dynamic testing (Paris law - fatigue crack growth)
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